These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Kenny The Shark
Crowning Moment of Funny: A crazed Kenny chasing one of Grace's patients who has a fear of sharks in "Simply Irresistible".
His delight at being cured and no longer needing Grace's services (Kat discovered that he smelled like seals because he visited them at the zoo, which naturally made Kenny wig out since seal is his favorite thing to eat) and Grace's deadpan displeasure about the turn of events are also hilarious.
Idiot Ball: Kat in "Whaling on Kenny". Kat had previously (since "Whaling on Kenny" was in Season 2) established as being a near expert on sharks, especially tiger sharks. Why was it a shocking revelation that orcas eat them?
In another episode, a pet trainer who repeatedly mistreated her students (especially Kenny) brought in a seal as a new pupil. When Kenny (who eats seals) naturally goes berserk. The trainer begins berating Kenny just in time to be caught by Kat who's disturbed by the treatment Kenny's receiving and appalled when she finds out about the seal, calling the trainer out on her stupidity. Fortunately the trainer is willing to listen.
Nightmare Fuel: The bullying Kenny undergoes in "Whaling on Kenny". It doesn't help that Kat's completely oblivious to it until Oscar informs her orcas (the species of whale to which Kenny's new "friend", Buster belongs) eat Tiger Sharks and that when Kat confronts him, Buster attacks her.